import React, { Component } from 'react'

export default class Count extends Component {

  increment = ()=>{
    const {value} = this.selectNumber;
    this.props.add(parseInt(value));
  }

  decrement = ()=>{
    const {value} = this.selectNumber;
    this.props.sub(parseInt(value));
  }

  incrementIfOdd = ()=>{
    const {value} = this.selectNumber;
    if(this.props.count % 2 !== 0){
      this.props.add(parseInt(value));
    }
  }

  //异步加
  incrementAsync = ()=>{
    const {value} = this.selectNumber;
    this.props.addAsync(parseInt(value),300);
  }

  render() {
    return (
      <div>
        <h1>当前求和为:{this.props.count}</h1>
        <select ref={c => this.selectNumber = c}>
            <option value='1'>1</option>
            <option value='2'>2</option>
            <option value='3'>3</option>
        </select>&nbsp;
        <button onClick={this.increment}>+</button>&nbsp;
        <button onClick={this.decrement}>-</button>&nbsp;
        <button onClick={this.incrementIfOdd}>前求和为奇数再加</button>&nbsp;
        <button onClick={this.incrementAsync}>异步加</button>&nbsp;
      </div>
    )
  }
}
